Water Filter for Subak Irrigation

Bali has a long-established agricultural history, with a web of stunning rice terraces part of its historical significance. Apart from providing a livelihood for many Balinese, rice farming is also strongly linked to Bali’s social, cultural, and religious way of life. In the context of rice cultivation in Bali, Subak is a vital concept, with the term Subak having more than one meaning. The most well known is as a traditional water irrigation system for rice fields and terraces.

The physical structure of Subak irrigation starts from the main source of water on higher ground in the mountains. Flowing through weirs, dams and canals constructed to direct water, water spills into rice terraces and fields, then to the nearest river and down to the ocean. 

Due to the extensive and excessive use of agrochemicals in rice farming, the Subak water carries the excess of those chemical inputs downstream to other rice terraces and fields, and ultimately into the ocean, contaminating the water, destroying offshore corals, and disrupting the ecosystem. Steven Lansing, an American anthropologist, has studied this since 1985. 

Prior to commencing a rice farming project, Begawan, along with the local farmers, committed to implementing a more regenerative approach to rice farming, treating the chemically contaminated water used in irrigation. Before starting a new rice cycle early this year, Begawan installed a subsurface water filter for the Subak water that enters our rice fields using Akar Wangi. Akar Wangi, globally known as Vetiver (Vetiveria zizanioides), is a perennial bunchgrass of the Poaceae family, native to tropical Asia. With its capacity for fast growth, wide adaptability, and strong resistance, extensive research has acknowledged its “super absorbent” characteristics suitable for restoring polluted water. Therefore, many people use it for water conservation. In addition to Vetiver, we also planted Water Hyacinth (Pontederia crassipes), a floating perennial used worldwide in aquatic systems for wastewater purification. Water Hyacinth is very efficient in removing a vast range of pollutants, including heavy metals. (Sintia Dewi)